Compositions for inhibiting corrosion

ABSTRACT

The present disclosure relates to agents, compositions, and methods for inhibiting corrosion in various substrates, for example in metal substrates. The present disclosure also relates to compositions for inhibiting corrosion comprising at least one organic heterocyclic compound and at least one metal salt or mixed metal salt selected from rare earth, alkali earth and transition metals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/067,453, which is a division of U.S. Non-Provisional patentapplication Ser. No. 15/562,826, filed Sep. 28, 2017, which is a U.S.National Stage application of PCT/AU2016/050245, filed Mar. 31, 2016,which claims benefit from U.S. Provisional Patent Application No.62/141,084, filed Mar. 31, 2015. Each of the above referencedapplications is incorporated herein by reference in its entirety.

FIELD

The present disclosure relates to agents, compositions, and methods forinhibiting corrosion in various substrates, for example in metalsubstrates. The present disclosure also relates to compositions forinhibiting corrosion comprising at least one organic heterocycliccompound and at least one metal salt or mixed metal salt selected fromrare earth, alkali earth and transition metals.

BACKGROUND

Protection of substrates, such as metal substrates, against atmosphericcorrosion presents a difficult challenge and has significant economicimportance. A range of metal substrates requiring protection fromcorrosion typically include aluminium alloys used in the aerospaceindustry, ferrous metals, zinc metals and alloys used for protectivecoatings.

Pigment grade corrosion inhibitors used in organic primers are wellknown to require anionic species with inhibitor activity that havelimited, but effective, solubility in water. For these reasons, chromatebased corrosion inhibitor species have been preferred in both corrosioncontrol technologies applied on aluminium for protection againstatmospheric corrosion, for example provided in conversion coatings andhigh performance organic primers. The hexavalent chromate ion has provento be an excellent corrosion inhibitor for many metals and alloy systemsfor almost a decade. However, the toxic and carcinogenic nature of thechromate ion has been understood for some time and there has beenextensive research for almost 30 years for finding environmentallyacceptable replacements.

It is generally known that if toxicity, efficiency, and price areconsidered, the number of inorganic corrosion inhibitor speciesavailable for chromate replacement is limited essentially to a fewanionic species, including molybdates, phosphates, borates, silicatesand cyanamides. As a consequence, all commercial non-chromate corrosioninhibitor pigments are molybdates, phosphates, borates, silicates orcyanamides, or combinations of these compounds. In comparison tochromates, inherent limitations of their corrosion preventing mechanismrender the anionic species less effective inhibitors of corrosion, ingeneral, and specifically of atmospheric corrosion of aluminium.Consequently, it appears that inorganic chemistry is unable to produceinhibitors of atmospheric corrosion, which could be comparablyeffective, non-toxic alternative of the hexavalent chromate.

In contrast, a large array of organic corrosion inhibitors have beenmore recently known and applied in various corrosion controltechnologies. Excessive solubility in water and/or volatility of most ofthe known organic inhibitors are limitations when used in conversioncoating technologies and in organic coatings.

Considerable progress has been made with identifying alternativecorrosion inhibitors and the salts of transition metal and rare earthmetals offer possible alternatives for many applications, includingdeoxidising and pickling solutions, etchants, anodizing and conversioncoatings, primer paints and sealants. For example, cerium chloride wasfound in the early 80's (Hinton et al.) to be an excellent inhibitor foraluminium alloys. Alkali metal salts of carboxylic acids such ascinnamates have also been found to effectively inhibit the corrosion ofmild steel.

The combination of rare earth metal ions with an effective organicinhibitor has also been found to suppress both anodic and cathodicreactions (i.e. a mixed inhibitor). For example, Behrouzvaziri et al.(2008) and Blin et al. (2007) have shown with electrochemical studiesthat lanthanum hydroxy cinnamate provides inhibition of corrosion inchloride solutions. For aluminium alloys, Ho et al. (2006) and Markleyet al. (2007) demonstrated that cerium diphenyl phosphate and ceriumdibutyl phosphate were very good inhibitors of corrosion of aluminiumalloys. For example, U.S. Pat. No. 5,298,148 describes a range of powdercoating formulations selected from the group consisting of lanthanumacetate, lanthanum butyrate, lanthanum oxalate, lanthanum nitrate,lanthanum hydroxide, lanthanum oxide, and lanthanum tungstate.

Organic compounds with aromatic character such as carbocyclic andheterocyclic aromatic structures have also been found to be effectiveinhibitors of corrosion of aluminium and its alloys, and for example,can be provided with metal salts or in the form of a metal complex. Forexample, WO2004/085551 relates to a corrosion inhibiting coatingcomprising a rare earth-based organic compound and/or a combination of arare earth metal and an organic compound for coatings comprising anepoxy primer for the corrosion protection of metals. Most of the knownalternative chromate based corrosion inhibitors suffer from variousproblems including poor corrosion inhibiting activity or incompatibilitywith various coating compositions.

There is a need for identifying alternative corrosion inhibitorcompositions for protecting substrates, for example in metal substratessuch as metal alloys, which are chromate-free corrosion inhibitorcompositions.

SUMMARY

Research was undertaken to identify improved coating compositions andchromate-free corrosion inhibitors for protecting various substrates,such as metal substrates, from corrosion. During this research, it wasidentified that particular organic heterocyclic compounds comprising atleast one exocyclic sulphur group, such as a thiol or thione group,could be advantageously used as a corrosion inhibiting agent incombination with rare earth, alkali earth and transition metal salts, ina corrosion inhibiting composition.

In one aspect, there is provided a method of protecting a substrate fromcorrosion comprising applying a corrosion inhibitor composition to thesurface of a substrate, wherein the corrosion inhibitor compositioncomprises: at least one metal salt or mixed metal salt, wherein themetal is selected from the group consisting of Zn, La, Pr, Ce, Nd, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr; andat least one organic heterocyclic compound of Formula 1 or salt thereof:

wherein

A is a 5- or 6-membered aryl, heteroaryl or heterocyclic ring, which isoptionally substituted with one or more substituents and optionallyfused with one or more aryl or heteroaryl rings, wherein a dotted linerepresents one or more optional double bonds;

Y¹ is selected from S or SH, wherein a dotted line represents a doublebond when Y¹ is S or is absent when Y¹ is SH;

X¹ is selected from N, NH, O, and S;

X² is selected from N, NR⁵, O, S, CR⁶ and CR⁷R⁸;

R⁵ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R⁶, R⁷ and R⁸, are each independently selected from hydrogen, halo,thiol, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl andheteroaryl, in which each amino, alkyl, alkenyl, alkynyl, aryl orheteroaryl group may be optionally substituted.

For the organic heterocyclic compounds of Formula 1, R⁶, R⁷ and R⁸, areeach independently selected from hydrogen, halo, amino, C₁-C₁₀alkyl,C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino,alkyl, alkenyl, alkynyl, aryl or heteroaryl group may be optionallysubstituted.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH. X¹may be selected from N, NH, and S. X¹ may be selected from N and S. X¹may be selected from N and NH. X² may be selected from N, NH, O, and S.X² may be selected from N, NH, and S. X² may be selected from N and NH.X¹ and X² may be each independently selected from N, NH and S. X¹ and X²may be each lo independently selected from N and NH. X¹ may be selectedfrom N and NH, and X² may be selected from CR⁶ and CR⁷R⁸.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH, andX¹ and X² may each be independently selected from N, NH, and S. X¹ maybe further selected from N and S. X¹ may be further selected from N andNH. X² may be further selected from CR⁶ and CR⁷R⁸. X² may be furtherselected from N, NH, and S. X² may be further selected from N and NH. X¹and X² each may be further independently selected from N and NH.

The metals may be selected from at least one of Zn, Pr and Ce.

The substrate may be a metal substrate. It will be appreciated that themetal substrate can include any substrate material having at least aportion of its surface being metallic. The metal substrate may compriseany metal requiring protection from corrosion. The metal substrate maybe copper-containing alloys, for example copper-containing aluminiumalloys.

In another aspect, there is provided a corrosion inhibiting agent forprotecting substrates from corrosion, wherein the corrosion inhibitingagent is an organic heterocyclic compound of Formula 1 as hereindescribed, which may include any examples or embodiments thereof.

In another aspect, there is provided use of a composition comprising atleast one metal salt or mixed metal salt, wherein the metal is selectedfrom the group consisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho,Er, Tm, Yb, Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr; and at least one organicheterocyclic compound of Formula 1 as herein described, which mayinclude any examples or embodiments thereof, as a corrosion inhibitor,such as protecting substrates from corrosion.

In another aspect, there is provided a corrosion inhibitor compositioncomprising at least one metal salt or mixed metal salt, wherein themetal is selected from the group consisting of Zn, La, Pr, Ce, Nd, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr; andat least one organic heterocyclic compound of Formula 1 as hereindescribed, which may include any examples or embodiments thereof.

The corrosion inhibitor composition may comprise a film-forming organicpolymer. The composition may be a coating composition. The coatingcomposition may be a powder coating composition, for example a powdercoating composition suitable for use in powder coating of varioussteels. The coating composition may comprise one or more resins, forexample epoxy based resins. The coating composition may be a paintcomposition, for example an epoxy resin based paint composition. Thecoating composition may be a spray composition. It will be appreciatedthat the compositions can include one or more additives, such aspigments, fillers and extenders.

In another aspect, there is provided a process for preparing a corrosioninhibitor composition for application to a substrate comprising forminga composition by admixing a film-forming organic polymer and a corrosioninhibitor composition as herein described, which may include anyexamples or embodiments thereof.

In another aspect, there is provided a coated substrate comprising asubstrate coated with a corrosion inhibitor composition as hereindescribed, which may include any examples or embodiments thereof. Thecoated substrate may comprise one or more layers of coatings applied tothe substrate before and/or after the coating of the corrosion inhibitorcomposition. The corrosion inhibitor composition may be applied as adirect coating to the surface of the substrate. The corrosion inhibitorcomposition may comprise a film-forming organic polymer. The substratemay be a metal alloy. The coated substrate may be an aerospacecomponent.

It will be appreciated that any one or more of the embodiments orexamples as described above and herein for one aspect may also apply asembodiments to any other aspects described above.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of the present disclosure are described and illustratedherein, by way of example only, with reference to the accompanyingFigures in which:

FIG. 1 a is a table of corrosion values for a selection of corrosioninhibitor compositions for copper-containing aluminium alloy, AA7075;

FIG. 1 b is a table of corrosion values for a selection of corrosioninhibitor compositions for copper-containing aluminium alloy, AA7075;

FIG. 2 a is a table of corrosion values for a selection of corrosioninhibitor compositions for copper-containing aluminium alloy, AA2024;

FIG. 2 b is a table of corrosion values for a selection of corrosioninhibitor compositions for copper-containing aluminium alloy, AA2024;and

FIG. 3 is a graph showing polarisation resistance electrochemicalexperiments performed on a copper-containing aluminium alloy, AA2024,for a selection of corrosion inhibitor compositions.

DETAILED DESCRIPTION

The present disclosure describes the following various non-limitingexamples, which relate to investigations undertaken to identifyalternative chromate free corrosion inhibitors. It was surprisinglyfound that a selection of organic heterocyclic compounds comprising atleast one exocyclic thiol or thione group were advantageously useful ascorrosion inhibiting agents in combination with rare earth, alkali earthand transition metal salts, in a corrosion inhibiting composition. Itwas also surprisingly found that a selection of organic heterocycliccompounds comprising a single exocyclic thiol or thione group wereadvantageously useful as corrosion inhibiting agents that could also befurther advantageously combined with rare earth, alkali earth andtransition metal salts, in a corrosion inhibiting composition.Additionally, it was found that the combination of corrosion inhibitingagent and rare earth, alkali earth and transition metal salt providedsynergistic results compared to results obtained when individualcomponents were used separately at the same concentration allowing lowerconcentrations of both corrosion inhibiting agent and rare earth, alkaliearth or transition metal salt to be used as part of a corrosioninhibiting composition. Surprisingly, various selections of organicheterocyclic compounds as described herein were also found to be lesstoxic than other known corrosion inhibiting organic heterocycliccompounds.

General Terms

As used herein, the term “substrate” refers to any structure that mayrequire protection from corrosion and that can be cleaned and/orprotected and/or modified to provide unique properties. The substratemay comprise at least a portion of its surface being metallic or beingof any other material susceptible to corrosion. The substrate may be ametal substrate.

As used herein, the term “metal substrate” refers to a structure havingat least a portion of its surface being metallic that can be cleanedand/or protected and/or modified to provide unique properties. A “metalsubstrate” is not limited to any particular type of metallic surface,and in terms of applying a corrosion inhibiting coating, such metalsubstrates typically include copper-containing alloys, for examplecopper-containing aluminium alloys.

As used herein, the term “protective composition” refers to anycomposition suitable for use in providing some form of corrosionprotection to a substrate. For example, a protective composition caninclude a powder coating composition for use in protecting steel fromcorrosion, or a film-forming organic polymer based composition forprotecting an aluminium alloy from corrosion.

As used herein, the term “extender” or “extender pigment” when usedwithout qualification, refers to a type of pigment that is typicallyincorporated into a paint formulation to provide volume to the finalresulting coating after paint curing, although it can be added for otherreasons, such as to reduce cost. An extender can additionally oralternatively be an active component in making a total system morecorrosion resistant. Extenders which add volume are often referred to as“fillers” or “extenders/fillers.”

As used herein, the term “coating” refers to a polymeric material(organic or inorganic) that can be applied either as a liquid (e.g.,paint) or solid (e.g., powder) to a substrate to form a polymeric film.Such polymeric materials include, but are not limited to, powdercoatings, paints, sealants, conducting polymers, sol gels (e.g. Boegel™made by Boeing Co. having offices in Chicago, Ill.), silicates,silicones, zirconates, titanates, and the like. A “coating” is comprisedof a complex mixture of binders, solvents, pigments and additives. Manycoatings have one or more substances from each of the four categories.Coating properties, such as gloss and color, are related to the filmsurface, for example as a two-dimensional entity. However, the bulkproperties of a coating are related to its three-dimensional structure.Phase continuity is a volume concept, and the coating performance isdependent on the integrity of the binder phase.

As used herein, the term “film-forming organic polymer” or “film-formingpolymeric material” refers to any polymeric material that can be used tomake coatings, including monomers, co-monomers, resins or polymers. Thepolymeric material can also be referred to as a “binder”, and can beeither organic or inorganic. The organic polymeric material generallyhas a carbon backbone and the inorganic polymeric material generally hasa silicone backbone. Organic binders are made up of organic monomers andoligomers from which the binders generally derive their names. Examplesof these would be acrylic, epoxy, urethane, melamine, and so forth.Binders include epoxy-based resin binders such as a water reducibleepoxy-polyamide system (for organic polymeric materials) ornon-epoxy-based resin binders such as urethanes, ureas, acrylates,alkyds, melamines, polyesters, vinyls, vinyl esters, silicones,siloxanes, silicates, sulfides, silicate polymers, epoxy novolacs, epoxyphenolics, drying oils, hydrocarbon polymers, and the like.

As used herein, the term “weight percent (wt %)” when used withoutqualification, typically refers to the weight percent of a particularsolid component, e.g., pigment, extender, etc., as compared with allsolid components present, excluding polymeric resins. For example, ifthe only solid component present in the coating is acorrosion-inhibiting carbon pigment, the corrosion-inhibiting carbonpigment is considered to have a wt % of 100.

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps. The various embodiments disclosedand described in this specification can comprise, consist of, or consistessentially of the features and characteristics as variously describedherein. The word “comprise”, “comprises”, or “comprising” includes thoseembodiments that “consist of” or “consist essentially of” the featuresand characteristics as variously described.

Any discussion of documents, acts, materials, devices, articles or thelike which has been included in the present specification is solely forthe purpose of providing a context for the present disclosure. It is notto be taken as an admission that any or all of these matters form partof the prior art base or were common general knowledge in the fieldrelevant to the present disclosure as it existed before the prioritydate of each claim of this application.

Chemical Terms

As will be understood, an aromatic group means a cyclic group having 4m+2 π electrons, where m is an integer equal to or greater than 1. Asused herein, “aromatic” is used interchangeably with “aryl” to refer toan aromatic group, regardless of the valency of aromatic group. Thus,aryl refers to monovalent aromatic groups, bivalent aromatic groups andhigher multivalency aromatic groups.

The term “joined” refers to a ring, moiety or group that is joined to atleast one other ring, moiety or group by a single covalent bond.

The term “fused” refers to one or more rings that share at least twocommon ring atoms with one or more other rings.

A heteroaromatic group is an aromatic group or ring containing one ormore heteroatoms, such as N, O, S, Se, Si or P. As used herein,“heteroaromatic” is used interchangeably with “heteroaryl”, and aheteroaryl group refers to monovalent aromatic groups, bivalent aromaticgroups and higher multivalency aromatic groups containing one or moreheteroatoms.

The term “optionally substituted” means that a group is eithersubstituted or unsubstituted, at any available position. Substitutioncan be with one or more groups selected from, e.g., alkyl, alkenyl,alkynyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl,formyl, alkanoyl, cycloalkanoyl, aroyl, heteroaroyl, carboxyl,alkoxycarbonyl, cycloalkyloxycarbonyl, aryloxycarbonyl,heterocyclyloxycarbonyl, heteroaryloxycarbonyl, alkylaminocarbonyl,cycloalkylaminocarbonyl, arylaminocarbonyl, heterocyclylaminocarbonyl,heteroarylaminocarbonyl, cyano, alkoxy, cycloalkoxy, aryloxy,heterocyclyloxy, heteroaryloxy, alkanoate, cycloalkanoate, aryloate,heterocyclyloate, heteroaryloate, alkylcarbonylamino,cycloalkylcarbonylamino, arylcarbonylamino, heterocyclylcarbonylamino,heteroarylcarbonylamino, nitro, hydroxyl, halo, haloalkyl, haloaryl,haloheterocyclyl, haloheteroaryl, haloalkoxy, silylalkyl,alkenylsilylalkyl, alkynylsilylalkyl, and amino. The optionalsubstitution may be one or more groups selected from halo, alkyl,formyl, and amino. The optional substituents may include salts of thegroups, for example carboxylate salts. It will be appreciated that othergroups not specifically described may also be used.

“Alkyl” whether used alone, or in compound words such as alkoxy,alkylthio, alkylamino, dialkylamino or haloalkyl, represents straight orbranched chain hydrocarbons ranging in size from one to about 10 carbonatoms, or more. Thus alkyl moieties include, unless explicitly limitedto smaller groups, moieties ranging in size, for example, from one toabout 6 carbon atoms or greater, such as, methyl, ethyl, n-propyl,iso-propyl and/or butyl, pentyl, hexyl, and higher isomers, including,e.g., those straight or branched chain hydrocarbons ranging in size fromabout 6 to about 10 carbon atoms, or greater.

“Alkenyl” whether used alone, or in compound words such as alkenyloxy orhaloalkenyl, represents straight or branched chain hydrocarbonscontaining at least one carbon-carbon double bond, including, unlessexplicitly limited to smaller groups, moieties ranging in size from twoto about 6 carbon atoms or greater, such as, methylene, ethylene,1-propenyl, 2-propenyl, and/or butenyl, pentenyl, hexenyl, and higherisomers, including, e.g., those straight or branched chain hydrocarbonsranging in size, for example, from about 6 to about 10 carbon atoms, orgreater.

“Alkynyl” whether used alone, or in compound words such as alkynyloxy,represents straight or branched chain hydrocarbons containing at leastone carbon-carbon triple bond, including, unless explicitly limited tosmaller groups, moieties ranging in size from, e.g., two to about 6carbon atoms or greater, such as, ethynyl, 1-propynyl, 2-propynyl,and/or butynyl, pentynyl, hexynyl, and higher isomers, including, e.g.,those straight or branched chain hydrocarbons ranging in size from,e.g., about 6 to about 10 carbon atoms, or greater.

“Cycloalkyl” represents a mono- or polycarbocyclic ring system ofvarying sizes, e.g., from about 3 to about 10 carbon atoms, e.g.,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or cycloheptyl. Theterm cycloalkyloxy represents the same groups linked through an oxygenatom such as cyclopentyloxy and cyclohexyloxy. The term cycloalkylthiorepresents the same groups linked through a sulfur atom such ascyclopentylthio and cyclohexylthio.

“Cycloalkenyl” represents a non-aromatic mono- or polycarbocyclic ringsystem, e.g., of about 3 to about 10 carbon atoms containing at leastone carbon-carbon double bond, e.g., cyclopentenyl, cyclohexenyl orcycloheptenyl. The term “cycloalkenyloxy” represents the same groupslinked through an oxygen atom such as cyclopentenyloxy andcyclohexenyloxy. The term “cycloalkenylthio” represents the same groupslinked through a sulfur atom such as cyclopentenylthio andcyclohexenylthio.

The terms, “carbocyclic” and “carbocyclyl” represent a ring systemwherein the ring atoms are all carbon atoms, e.g., of about 3 to about10 carbon atoms, and which may be aromatic, non-aromatic, saturated, orunsaturated, and may be substituted and/or carry fused rings. Examplesof such groups include benzene, cyclopentyl, cyclohexyl, or fully orpartially hydrogenated phenyl, naphthyl and fluorenyl.

“Aryl” whether used alone, or in compound words such as arylalkyl,aryloxy or arylthio, represents: (i) an optionally substituted mono- orpolycyclic aromatic carbocyclic moiety, e.g., of about 6 to about 60carbon atoms, such as phenyl, naphthyl or fluorenyl; or, (ii) anoptionally substituted partially saturated polycyclic carbocyclicaromatic ring system in which an aryl and a cycloalkyl or cycloalkenylgroup are fused together to form a cyclic structure such as atetrahydronaphthyl, indenyl ,indenyl or fluorene ring.

“Heterocyclyl” or “heterocyclic” whether used alone, or in compoundwords such as heterocyclyloxy represents: (i) an optionally substitutedcycloalkyl or cycloalkenyl group, e.g., of about 3 to about 60 ringmembers, which may contain one or more heteroatoms such as nitrogen,oxygen, or sulfur (examples include pyrrolidinyl, morpholino,thiomorpholino, or fully or partially hydrogenated thienyl, furyl,pyrrolyl, thiazolyl, oxazolyl, oxazinyl, thiazinyl, pyridyl andazepinyl); (ii) an optionally substituted partially saturated polycyclicring system in which an aryl (or heteroaryl) ring and a heterocyclicgroup are fused together to form a cyclic structure (examples includechromanyl, dihydrobenzofuryl and indolinyl); or (iii) an optionallysubstituted fully or partially saturated polycyclic fused ring systemthat has one or more bridges (examples include quinuclidinyl anddihydro-1,4-epoxynaphthyl).

“Heteroaryl” or “hetaryl” whether used alone, or in compound words suchas heteroaryloxy represents: (i) an optionally substituted mono- orpolycyclic aromatic organic moiety, e.g., of about 1 to about 10 ringmembers in which one or more of the ring members is/are element(s) otherthan carbon, for example nitrogen, oxygen, sulfur or silicon; theheteroatom(s) interrupting a carbocyclic ring structure and having asufficient number of delocalized pi electrons to provide aromaticcharacter, provided that the rings do not contain adjacent oxygen and/orsulfur atoms. Typical 6-membered heteroaryl groups are pyrazinyl,pyridazinyl, pyrazolyl, pyridyl and pyrimidinyl. All regioisomers arecontemplated, e.g., 2-pyridyl, 3-pyridyl and 4-pyridyl. Typical5-membered heteroaryl rings are furyl, imidazolyl, oxazolyl, isoxazolyl,isothiazolyl, oxadiazolyl, pyrrolyl, 1,3,4-thiadiazolyl, thiazolyl,thienyl, triazolyl, and silole. All regioisomers are contemplated, e.g.,2-thienyl and 3-thienyl. Bicyclic groups typically are benzo-fused ringsystems derived from the heteroaryl groups named above, e.g.,benzofuryl, benzimidazolyl, benzthiazolyl, indolyl, indolizinyl,isoquinolyl, quinazolinyl, quinolyl and benzothienyl; or, (ii) anoptionally substituted partially saturated polycyclic heteroaryl ringsystem in which a heteroaryl and a cycloalkyl or cycloalkenyl group arefused together to form a cyclic structure such as a tetrahydroquinolylor pyrindinyl ring.

“Formyl” represents a —CHO moiety.

“Alkanoyl” represents a —C(═O)-alkyl group in which the alkyl group isas defined supra. An alkanoyl group may range in size from about C₂-C₂₀.One example is acyl.

“Aroyl” represents a —C(═O)-aryl group in which the aryl group is asdefined supra. An aroyl group may range in size from about C₇-C₂₀.Examples include benzoyl and 1-naphthoyl and 2-naphthoyl.

“Heterocycloyl” represents a —C(═O)-heterocyclyl group in which theheterocylic group is as defined supra. An heterocycloyl may range insize from about C₄-C₂₀.

“Heteroaroyl” represents a —C(═O)-heteroaryl group in which theheteroaryl group is as defined supra. A heteroaroyl group may range insize from about C₆-C₂₀. An example is pyridylcarbonyl.

“Carboxyl” represents a —CO₂H moiety.

“Oxycarbonyl” represents a carboxylic acid ester group —CO₂R which islinked to the rest of the molecule through a carbon atom.

“Alkoxycarbonyl” represents an —CO₂-alkyl group in which the alkyl groupis as defined supra. An alkoxycarbonyl group may range in size fromabout C₂-C₂₀. Examples include methoxycarbonyl and ethoxycarbonyl.

“Aryloxycarbonyl” represents an —CO₂-aryl group in which the aryl groupis as defined supra. Examples include phenoxycarbonyl andnaphthoxycarbonyl.

“Heterocyclyloxycarbonyl” represents a —CO₂-heterocyclyl group in whichthe heterocyclic group is as defined supra.

“Heteroaryloxycarbonyl” represents a —CO₂-heteroaryl group in which theheteroaryl group is as defined supra.

“Aminocarbonyl” represents a carboxylic acid amide group —C(═O)NHR or—C(═O)NR₂ which is linked to the rest of the molecule through a carbonatom.

“Alkylaminocarbonyl” represents a —C(═O)NHR or —C(═O)NR₂ group in whichR is an alkyl group as defined supra.

“Arylaminocarbonyl” represents a —C(═O)NHR or —C(═O)NR₂ group in which Ris an aryl group as defined supra.

“Heterocyclylaminocarbonyl” represents a —C(═O)NHR or —C(═O)NR₂ group inwhich R is a heterocyclic group as defined supra. NR₂ may for example bea heterocyclic ring, which is optionally substituted.

“Heteroarylaminocarbonyl” represents a —C(═O)NHR or —C(═O)NR₂ group inwhich R is a heteroaryl group as defined supra. NR₂ may for example be aheteroaryl ring, which is optionally substituted.

“Cyano” represents a —CN moiety.

“Hydroxyl” represents a —OH moiety.

“Alkoxy” represents an —O-alkyl group in which the alkyl group is asdefined supra. Examples include methoxy, ethoxy, n-propoxy, iso-propoxy,and the different butoxy, pentoxy, hexyloxy and higher isomers.

“Aryloxy” represents an —O-aryl group in which the aryl group is asdefined supra. Examples include, without limitation, phenoxy andnaphthoxy.

“Alkenyloxy” represents an —O-alkenyl group in which the alkenyl groupis as defined supra. An example is allyloxy.

“Heterocyclyloxy” represents an —O-heterocyclyl group in which theheterocyclic group is as defined supra.

“Heteroaryloxy” represents an —O-heteroaryl group in which theheteroaryl group is as defined supra. An example is pyridyloxy.

“Alkanoate” represents an —OC(═O)—R group in which R is an alkyl groupas defined supra.

“Aryloate” represents a —OC(═O)—R group in which R is an aryl group asdefined supra.

“Heterocyclyloate” represents an —OC(═O)—R group in which R is aheterocyclic group as defined supra.

“Heteroaryloate” represents an —OC(═O)—R group in which P is aheteroaryl group as defined supra.

“Amino” represents an —NH₂ moiety.

“Alkylamino” represents an —NHR or —NR₂ group in which R is an alkylgroup as defined supra. Examples include, without limitation,methylamino, ethylamino, n-propylamino, isopropylamino, and thedifferent butylamino, pentylamino, hexylamino and higher isomers.

“Arylamino” represents an —NHR or —NR₂ group in which R is an aryl groupas defined supra. An example is phenylamino.

“Heterocyclylamino” represents an —NHR or —NR₂ group in which R is aheterocyclic group as defined supra. NR₂ may for example be aheterocyclic ring, which is optionally substituted.

“Heteroarylamino” represents a —NHR or —NR₂ group in which R is aheteroaryl group as defined supra. NR₂ may for example be a heteroarylring, which is optionally substituted.

“Carbonylamino” represents a carboxylic acid amide group —NHC(═O)R thatis linked to the rest of the molecule through a nitrogen atom.

“Alkylcarbonylamino” represents a —NHC(═O)R group in which R is an alkylgroup as defined supra.

“Arylcarbonylamino” represents an —NHC(═O)R group in which R is an arylgroup as defined supra.

“Heterocyclylcarbonylamino” represents an —NHC(═O)R group in which R isa heterocyclic group as defined supra.

“Heteroarylcarbonylamino” represents an —NHC(═O)R group in which R is aheteroaryl group as defined supra.

“Nitro” represents a —NO₂ moiety.

“Aldehyde” represents a —C(═O)H group.

“Alkanal” represents an alkyl-(C═O)H group in which the alkyl group isas defined supra.

“Alkylsilyl” represents an alkyl group that is linked to the rest of themolecule through the silicon atom, which may be substituted with up tothree independently selected alkyl groups in which each alkyl group isas defined supra.

“Alkenylslyl” presents an alkenyl group that is linked to the rest ofthe molecule through the silicon atom, which may be substituted with upto three independently selected alkenyl groups in which each alkenylgroup is as defined supra.

“Alkynylsilyl” presents an alkynyl group that is linked to the rest ofthe molecule through the silicon atom, which may be substituted with upto three independently selected alkynyl groups in which each alkenylgroup is as defined supra.

The term “halo” or “halogen” whether employed alone or in compound wordssuch as haloalkyl, haloalkoxy or haloalkylsulfonyl, represents fluorine,chlorine, bromine or iodine. Further, when used in compound words suchas haloalkyl, haloalkoxy or haloalkylsulfonyl, the alkyl may bepartially halogenated or fully substituted with halogen atoms which maybe independently the same or different. Examples of haloalkyl include,without limitation, —CH₂CH₂F, —CF₂CF₃ and —CH₂CHFCl. Examples ofhaloalkoxy include, without limitation, —OCHF₂, —OCF₃, —OCH₂CCl₃,—OCH₂CF₃ and —OCH₂CH₂CF₃. Examples of haloalkylsulfonyl include, withoutlimitation, —SO₂CF₃, —SO₂CCl₃, —SO₂CH₂CF₃ and —SO₂CF₂CF₃.

The terms “thiol”, “thio”, “mercapto” or “mercaptan” refer to anyorganosulphur group containing a sulphurhydryl moiety —SH, whichincludes a R—SH group where R is a moiety containing a carbon atom forcoordination to the —SH moiety, for example an alkylsulphur group asdefined supra. For example, the thiol or mercapto group may be asulphurhydryl moiety —SH.

The terms “thione”, “thioketones” or “thiocarbonyls” refer to anyorganosulphur group containing a —C═S moiety, which includes a R—C═Sgroup, for example where R is an alky group defined supra. For example,the thione group may be a —C═S moiety.

The term “exocyclic” refers to an atom or group that is attachedexternally to a cyclic ring system of a heteroaryl or heterocycliccompound, which contrasts with an “endocyclic” atom or group that iswithin the ring system such that the atoms form a part of the ringsystem of the heteroaryl or heterocyclic compound.

The compounds described herein may include salts, solvates, hydrates,isomers, tautomers, racemates, stereoisomers, enantiomers ordiastereoisomers of those compounds. For example salts may includesodium, potassium, calcium, nitrates, phosphates, sulphates, andchlorides. In one embodiment the compounds include salts thereofselected from sodium salts.

Corrosion Inhibiting Agents

The corrosion inhibiting agents of the present disclosure may beselected from at least one organic heterocyclic compound comprising atleast one exocyclic sulphur group, for example a thiol or thione group.The corrosion inhibiting agents of the present disclosure may also beselected from at least one organic heterocyclic compound comprising asingle exocyclic sulphur group, for example a thiol or thione group. Theorganic heterocyclic compounds may be each optionally substituted andoptionally fused with one or more substituents or groups. The organicheterocyclic compounds may be selected from an optionally substituted,optionally fused, heteroaryl or heterocyclic compound comprising atleast one exocyclic thiol or thione group. The organic heterocycliccompound may be selected from optionally substituted heteroaryl orheterocyclic compound comprising at least one exocyclic thiol or thionegroup and at least one endocyclic heteroatom selected from N, O and S.The organic heterocyclic compound may include salts of the at least oneexocyclic thiol groups, for example, thiol sodium salt.

The one or more organic heterocyclic compounds may each be selected froman optionally substituted, optionally fused, 5 or 6-membered mono orbicyclic heteroaryl or heterocyclic compound comprising at least oneexocyclic sulphur group selected from a thiol and thione. The exocyclicsulphur group may be a thiol.

The at least one organic heterocyclic compound may be selected from acompound of Formula 1 or salt thereof:

wherein

A is a 5- or 6-membered aryl, heteroaryl or heterocyclic ring, which isoptionally substituted with one or more substituents and optionallyfused with one or more aryl or heteroaryl rings, wherein a dotted linerepresents one or more optional double bonds;

Y¹ is selected from S or SH, wherein a dotted line represents a doublebond when Y¹ is S or is absent when Y¹ is SH;

X¹ is selected from N, NH, O, and S;

X² is selected from N, NR⁵, O, S, CR⁶ and CR⁷R⁸;

R⁵ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R⁶, R⁷ and R⁸, are each independently selected from hydrogen, halo,thiol, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl andheteroaryl, in which each amino, alkyl, alkenyl, alkynyl, aryl orheteroaryl group may be optionally substituted.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH. X¹may be selected from N, NH, and S. X¹ may be selected from N and S. X¹may be selected from N and NH. X² may be selected from N, NH, O, and S.X² may be selected from N, NH, and S. X² may be selected from N and NH.X¹ and X² may be each independently selected from N, NH and S. X¹ and X²may be each independently selected from N and NH. X¹ may be selectedfrom N and NH, and X² may be selected from CR⁶ and CR⁷R⁸.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH, andX¹ and X² may each be independently selected from N, NH, and S. X¹ maybe further selected from N and S. X¹ may be further selected from N andNH. X² may be further selected from CR⁶ and CR⁷R⁸. X² may be furtherselected from N, NH, and S. X² may be further selected from N and NH. X¹and X² each may be further independently selected from N and NH.

Optionally fused groups of ring A may be monocyclic or polycyclic.Optional fused groups of the A ring may be optionally substituted mono-or bicyclic aryl, heteroaryl or heterocyclic ring, for example where acompound of Formula 1 is a bicyclic compound. The monocyclic aryl groupsmay be an optionally substituted 6 membered ring, such as benzene. Thepolycyclic aryl groups may be two or more optionally substituted6-member rings fused together, such as naphthalene, anthracene, pyrene,tetracene, and pentacene. The heteroaryl groups may be selected from5-membered monocyclic rings, such as thiophene, furan, pyrrole, silole,imidazole, 1,3-thiazole, 1,3,4-oxadiazole, 1,3,4-thiadiazole, or 6membered rings, such as pyridine and triazine, wherein each ring may beoptionally substituted.

Optional substituents of ring A ring may be selected from halo, cyano,amino, hydroxy, alkanoic acid, alkanoate salt, carbamoyl,C₁-C₁₀alkyloxycarbonyl, C₁-C₁₀alkylamino, C₃-C₁₀cycloalkyl,C₂-C₁₀alkenyl, C₃-C₁₀cycloalkenyl, C₂-C₁₀alkynyl, C₃-C₁₀cycloalkynyl,aryl and arylC₁-C₁₀alkyl, heteroaryl and heteroarylC₁-C₁₀alkyl,C₁-C₁₀alkyloxy, C₃-C₁₀cycloalkyloxy and wherein amino, alkanoic acid,alkanoic salt, alkyloxycarbonyl, alkyl, haloalkyl, alkylamino,cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl,arylalkyl, heteroaryl, heteroarylalkyl, alkyloxy and cycloalkyloxy ineach occurrence may be optionally substituted, for example furthersubstituted with one or more of halo, hydroxyl, amino, nitro, carboxylicacid. The optional substitution may be any one or more groups selectedfrom halo, alkyl, formyl, and amino. The optional substituents mayinclude salts of the functional groups, for example carboxylate salts.

Ring A may be heterocyclic, for example an unsaturated heterocycliccompound. Ring A may be heteroaromatic or partially unsaturated. Forexample, ring A may contain one or more double bonds between ring atoms.Ring A may also contain one or more optional substituents and optionalfused groups. Ring A may be a monocyclic 5 or 6 membered heteroaryl orheterocyclic ring. Ring A may be a bicyclic ring comprising two ringsjoined together that are each independently selected from 5 and 6membered rings. Ring A may be a bicyclic ring comprising two rings fusedtogether that are each independently selected from 5 and 6 memberedrings. Ring A may be a bicyclic heteroaryl or heterocyclic ringcontaining a 5 membered heterocyclic ring fused to a 6 membered aryl,carbocyclic, heterocyclic or heteroaryl ring.

A further advantage can be provided when the at least one organicheterocyclic compound selected from a compound of Formula 1 or saltthereof provides a single exocyclic thiol or thione group. For example,the at least one organic heterocyclic compound may be selected from acompound of Formula 1 or salt thereof:

wherein

A is a 5- or 6-membered aryl, heteroaryl or heterocyclic ring, which isoptionally substituted with one or more substituents and optionallyfused with one or more aryl or heteroaryl rings, wherein a dotted linerepresents one or more optional double bonds;

Y¹ is selected from S or SH, wherein a dotted line represents a doublebond when Y¹ is S or is absent when Y¹ is SH;

X¹ is selected from N, NH, O, and S;

X² is selected from N, NR⁵, O, S, CR⁶ and CR⁷R⁸;

R⁵ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R⁶, R⁷ and R⁸, are each independently selected from hydrogen, halo,amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl and heteroaryl,in which each amino, alkyl, alkenyl, alkynyl, aryl or heteroaryl groupmay be optionally substituted.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH. X¹may be selected from N, NH, and S. X¹ may be selected from N and S. X¹may be selected from N and NH. X² may be selected from N, NH, O, and S.X² may be selected from N, NH, and S. X² may be selected from N and NH.X¹ and X² may be each independently selected from N, NH and S. X¹ and X²may be each independently selected from N and NH. X¹ may be selectedfrom N and NH, and X² may be selected from CR⁶ and CR⁷R⁸.

For the organic heterocyclic compounds of Formula 1, Y¹ may be SH, andX¹ and X² may each be independently selected from N, NH, and S. X¹ maybe further selected from N and S. X¹ may be further selected from N andNH. X² may be further selected from CR⁶ and CR⁷R⁸. X² may be furtherselected from N, NH, and S. X² may be further selected from N and NH. X¹and X² each may be further independently selected from N and NH.

Optionally fused groups of ring A may be monocyclic or polycyclic.Optional fused groups of the A ring may be optionally substituted mono-or bicyclic aryl, heteroaryl or heterocyclic ring, for example where acompound of Formula 1a is a bicyclic compound. The monocyclic arylgroups may be an optionally substituted 6 membered ring, such asbenzene. The polycyclic aryl groups may be two or more optionallysubstituted 6-member rings fused together, such as naphthalene,anthracene, pyrene, tetracene, and pentacene. The heteroaryl groups maybe selected from 5-membered monocyclic rings, such as thiophene, furan,pyrrole, silole, imidazole, 1,3-thiazole, 1,3,4-oxadiazole,1,3,4-thiadiazole, or 6 membered rings, such as pyridine and triazine,wherein each ring may be optionally substituted.

Optional substituents of ring A ring may be selected from halo, cyano,amino, hydroxy, alkanoic acid, alkanoate salt, carbamoyl,C₁-C₁₀alkyloxycarbonyl, C₁-C₁₀alkyl, C₁-C₁₀haloalkyl, C₁-C₁₀alkylamino,C₃-C₁₀cycloalkyl, C₂-C₁₀alkenyl, C₃-C₁₀cycloalkenyl, C₂-C₁₀alkynyl,C₃-C₁₀cycloalkynyl, aryl and arylC₁-C₁₀alkyl, heteroaryl andheteroarylC₁-C₁₀alkyl, C₁-C₁₀alkyloxy, C₃-C₁₀cycloalkyloxy and whereinamino, alkanoic acid, alkanoic salt, alkyloxycarbonyl, alkyl, haloalkyl,alkylamino, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl,aryl, arylalkyl, heteroaryl, heteroarylalkyl, alkyloxy and cycloalkyloxyin each occurrence may be optionally substituted, for example furthersubstituted with one or more of halo, hydroxyl, amino, nitro, carboxylicacid. The optional substitution may be any one or more groups selectedfrom halo, alkyl, formyl, and amino. The optional substituents mayinclude salts of the functional groups, for example carboxylate salts.

Ring A may be heterocyclic, for example an unsaturated heterocycliccompound. Ring A may be heteroaromatic or partially unsaturated. Forexample, ring A may contain one or more double bonds between ring atoms.Ring A may also contain one or more optional substituents and optionalfused groups. Ring A may be a monocyclic 5 or 6 membered heteroaryl orheterocyclic ring. Ring A may be a bicyclic ring comprising two ringsjoined together that are each independently selected from 5 and 6membered rings. Ring A may be a bicyclic ring comprising two rings fusedtogether that are each independently selected from 5 and 6 memberedrings. Ring A may be a bicyclic heteroaryl or heterocyclic ringcontaining a 5 membered heterocyclic ring fused to a 6 membered aryl,carbocyclic, heterocyclic or heteroaryl ring.

The at least one organic heterocyclic compound may be selected from acompound of Formula 1(a) or salts thereof:

wherein

A, Y¹, X¹ and X² are defined according to Formula 1 as described above;

A¹, A² and A³ are each independently selected from C═O, C═S, N, NR¹³, O,S, SO₂, CR¹⁴, CR¹⁵R¹⁶;

R¹³ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R¹⁴, R¹⁵ and R¹⁶, are each independently selected from hydrogen, halo,thiol, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl andheteroaryl, in which each amino, alkyl, alkenyl, alkynyl, aryl orheteroaryl group may be optionally substituted, and optionally two ofR¹³, R¹⁴, R¹⁵ and R¹⁶, join together to form an optionally substitutedaryl or heteroaryl ring fused to the A ring.

In an embodiment, A¹ and A³ are CR¹⁴. In another embodiment, R¹⁴ isselected from amino and thiol. In another embodiment, A¹ and A³ are eachindependently selected from C—SH and C—NH₂. In another embodiment, A¹and A³ are C—SH. In another embodiment, Y¹ is SH. In another embodiment,X¹ and X² are N. In another embodiment, A² is N. Some specific examplesof compounds of Formula 1(a) are provided as follows:

The at least one organic heterocyclic compound may be selected from acompound of Formula 1(a)(i) or salts thereof:

wherein

A is a 5- or 6-membered aryl, heteroaryl or heterocyclic ring, which isoptionally substituted with one or more substituents and optionallyfused with one or more aryl or heteroaryl rings, wherein a dotted linerepresents one or more optional double bonds;

A², X¹ and X² are each independently selected from N, NH, O, and S;

Y¹, Y² and Y³ are each independently selected from S or SH, wherein thedotted line represents a double bond when Y¹ is S or is absent when Y¹is SH;

X¹ and X² are defined according to Formula 1 as described above;

A¹, A² and A³ are each independently selected from C═O, C═S, N, NR¹³, O,S, SO₂, CR¹⁴, CR¹⁵R¹⁶; and

R¹⁴, R¹⁵ and R¹⁶ are defined according to Formula 1a as described above.

In an embodiment, A², X¹ and X² are N. In another embodiment, Y¹, Y² andY³ are SH.

Some specific examples of compounds of Formula 1(a)(i) are provided asfollows:

Further advantages may be provided by a single exocyclic thiol or thionegroup, including salts thereof. In one embodiment, the at least oneorganic heterocyclic compound may be selected from a compound of Formula1(b) or salt thereof:

wherein

A ring is an optionally substituted 5-membered heterocyclic ring,wherein a dotted line represents one or more optional double bonds;

X¹, X² and Y¹ are defined according to Formula 1 as described above;

A¹ and A² are each independently selected from C═O, C═S, N, NR¹³, O, S,SO₂, CR¹⁴ and CR¹⁵R¹⁶; and are optionally joined together to form anoptionally substituted aryl, heteroaryl or heterocyclic ring J that isfused to the A ring;

R¹³ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R¹⁴, R¹⁵ and R¹⁶, are each independently selected from hydrogen, halo,amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl and heteroaryl,in which each amino, alkyl, alkenyl, alkynyl, aryl or heteroaryl groupmay be optionally substituted, and optionally two of R¹³, R¹⁴, R¹⁵ andR¹⁶, join together to form an optionally substituted aryl or heteroarylring fused to the A ring.

Some specific examples of compounds of Formula 1(b) are provided asfollows:

The at least one organic heterocyclic compound may be selected from acompound of Formula 1(b)(i) or salt thereof:

wherein

A ring is an optionally substituted 5-membered heterocyclic ring,wherein a dotted line represents one or more optional double bonds;

X¹, X² and Y¹ are defined according to Formula 1b as described above;

A¹ and A² are each independently selected from N, NR¹³, O, S, CR¹⁴ andCR¹⁵R¹⁶;

R¹³ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R¹⁴, R¹⁵ and R¹⁶ are defined according to Formula 1b as described above.

Some specific examples of compounds of Formula 1(b)(i) are provided asfollows:

The at least one organic heterocyclic compound may be selected from acompound of Formula 1(b)(ii) or salt thereof:

wherein

A ring is an optionally substituted 5-membered heterocyclic ring and Jring is an optionally substituted 6-membered aryl or heterocyclic ring,wherein a dotted line represents one or more optional double bonds;

X¹, X² and Y¹ are defined according to Formula 1a as described above;

J¹, J², J³ and J⁴ are each independently selected from N, NR¹³, O, S,CR¹⁴ and CR¹⁵R¹⁶;

R¹³ is selected from hydrogen, amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl,C₂-C₁₀alkynyl, aryl and heteroaryl, in which each amino, alkyl, alkenyl,alkynyl, aryl or heteroaryl group may be optionally substituted; and

R¹⁴, R¹⁵ and R¹⁶, are each independently selected from hydrogen, halo,amino, C₁-C₁₀alkyl, C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl and heteroaryl,in which each amino, alkyl, alkenyl, alkynyl, aryl or heteroaryl groupmay be optionally substituted.

Some specific examples of compounds of Formula 1(b)(ii) are provided asfollows:

It will be appreciated that any of the embodiments or examples describedabove or herein for Formula 1 may also provide embodiments for anycompounds of Formula 1(a), 1(a)(i), 1(b), 1(b)(i) or 1(b)(ii).

The organic compounds may exist as one or more stereoisomers. Thevarious stereoisomers can include enantiomers, diastereomers andgeometric isomers. Those skilled in the art will appreciate that onestereoisomer may be more active than the other(s). In addition, theskilled person would know how to separate such stereoisomers.Accordingly, the present disclosure comprises mixtures, individualstereoisomers, and optically active mixtures of the compounds describedherein.

Some specific examples of heteroaryl and heterocyclic organic compoundsof Formula 1 are shown in Table 1 as follows:

TABLE 1 Ref. No. Chemical Name Chemical Structure 1 2-mercaptobenzimidazole (MBI)

2 3a,4- dihydrothiazolo[4,5- c]pyridine-2-thiol

3 benzo[d]thiazole- 2(3H)-thione

4 1,2,4-triazole-3-thiol

5 2-amino,5-mercapto- 1,2,4-thiadiazole

6 5-methyl-2-mercapto- 1,3,4-thiadiazole

7 4-amino-5-phenyl-3- mercapto-1,2,4-triazole

8 5-mercapto-1- tetrazole-1H-acetic acid, sodium salt

9 4,6-diamino-2- mercaptopyrimidine

10 4-amino-2- mercaptopyrimidine

11 2,6-diamino-4- mercaptopyrimidine

12 9H-purine-8-thiol

13 1H-imidazo[4,5- b]pyrazine-2-thiol

14 S-triazole-[4,3-a]- pyridine-3-thione

15 2- mercaptobenzimidazole

16 1,2,4-triazole-3-thiol

17 3-amino-5-mercapto- 1,2,4-triazole

18 2-mercaptopyrimidine

19 2-mercaptonicotinate, sodium salt

20 4-mercaptobenzoate, sodium salt

21 6-mercaptonicotinate, sodium salt

22 1,3,5-triazine-2,4,6- trithiol

23 1,3,5-triazine-2,4,6- trithiol, trisodium salt

Metal Salts

The metal salts or mixed metal salts of the corrosion inhibitingcompositions may be selected from alkali earth metals, transition metalsand rare earth metal salts, for example a group consisting of Zn, La,Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ce, Co, Y, Bi, Cd, Pb,Ag, Sb, Sn, Cu, Fe, Ni, Li, Ca, Sr, Mg, Zr, Nd, Ba, Sc, and anycombinations thereof. The corrosion inhibitor compositions may compriseat least one metal salt or mixed metal salt, wherein the metal isselected from the group consisting of Zn, La, Pr, Ce, Co, Y, Ca, Sr, Ba,Sc, and Zr. It will be appreciated that a mixed metal salt may beprovided by a combination comprising two or more metals. For example,the mixed metal salt may comprise two or more metals selected from anytwo or more of Zn, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,Ce, Co, Y, Bi, Cd, Pb, Ag, Sb, Sn, Cu, Fe, Ni, Li, Ca, Sr, Mg, Zr, Nd,Ba, and Sc. The metals may be selected from at least one of Zn, Pr andCe. The metal may be Zn. The metal may be Ce. The metal may be Pr. Someexamples of salts that may be used are nitrate, chloride and acetatesalts. It will be appreciated that the metals may have differentoxidation states. For example, the typical oxidation state for Zn is +2.The typical oxidation states for Pr are +2, +3 and/or +4. The typicaloxidation states for Ce are +2, +3 and +4. It will be appreciated thatvarious combinations and groups of the above mentioned metal salts ormixed metal salts, may be used in the compositions of the presentdisclosure.

Substrates for Corrosion Protection

Substrates that may be protected from corrosion by the corrosioninhibiting agents or compositions thereof as described herein may bemetal substrates. It will be appreciated that the metal substrate caninclude any substrate material having at least a portion of its surfacebeing metallic, for example a portion of its external surface beingmetallic. The metal substrate may comprise any metal requiringprotection from corrosion. The metal substrate may comprise a metal oralloy selected from aluminium, for example aluminium alloys. The metalsubstrate may be an aluminium alloy, for example alloys of aluminiumwith one or more metals selected from the group consisting of copper,magnesium, manganese, silicon, tin and zinc. The aluminium alloys may bean alloy comprising copper. The metal substrate may be acopper-containing alloy, such as copper-containing aluminium alloy. Theamount of copper in the alloy may be less than about 20%, less thanabout 18%, less than about 16%, less than about 14%, less than about12%, less than about 10%, less than about 8%, or less than about 6%. Thealuminium alloy may be an aerospace alloy, for example AA2XXX and AA7XXXtype. For example the aluminium alloy may be AA2024 and AA7075 type. Thealuminium alloy may be an automotive alloy, for example AA6XXX type. Thealuminium alloy may be a marine alloy, for example AA5XXX type.

Compositions and Formulations

The present disclosure also relates to compositions for inhibitingcorrosion comprising (a) at least one organic heterocyclic compound ofFormula 1 as described herein and (b) at least one metal selected fromrare earth, alkali earth and transition metals, as described herein, orany embodiments thereof. It will be appreciated that reference to anycombination of (a) and (b) in the composition described herein refers tothe individual components of (a) and (b) together in one composition andnot reaction products thereof.

For example, the corrosion inhibitor compositions may comprise (a) atleast one organic heterocyclic compound of Formula 1 as described hereinor any embodiments thereof and (b) at least one metal salt or mixedmetal salt, wherein the metal is selected from the group consisting ofZn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Co, Y, Ca,Sr, Ba, Sc, and Zr. For example, the at least one metal may be any oneof Zn, Ce and Pr; the at least one metal may be Zn; the at least onemetal may be Ce; or the at least one metal may be Pr.

The corrosion inhibitor composition may comprise (a) at least oneorganic heterocyclic compound of Formula 1(a) or salt thereof, asdescribed herein or any embodiments thereof and (b) at least one metalsalt or mixed metal salt, wherein the metal is selected from the groupconsisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr.

The corrosion inhibitor composition may comprise (a) at least oneorganic heterocyclic compound of Formula 1(a)(i) or salt thereof, asdescribed herein or any embodiments thereof and (b) at least one metalsalt or mixed metal salt, wherein the metal is selected from the groupconsisting of Zn, Pr and Ce.

The corrosion inhibitor composition may comprise (a) at least oneorganic heterocyclic compound of Formula 1(b) or salt thereof, asdescribed herein or any embodiments thereof and (b) at least one metalsalt or mixed metal salt, wherein the metal is selected from the groupconsisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr.

The corrosion inhibitor composition may comprise (a) at least oneorganic heterocyclic compound of Formula 1(b)(i) or salt thereof, asdescribed herein or any embodiments thereof and (b) at least one metalsalt or mixed metal salt, wherein the metal is selected from the groupconsisting of Zn, Pr and Ce.

The corrosion inhibitor composition may comprise (a) at least oneorganic heterocyclic compound of Formula 1(b)(ii) or salt thereof, asdescribed herein or any embodiments thereof and (b) at least one metalsalt or mixed metal salt, wherein the metal is selected from the groupconsisting of Zn, Pr and Ce.

Further advantages can be achieved wherein the concentration of thecorrosion inhibiting agents and metal salts or mixed metal salts areprovided at various concentration and ratio ranges. The concentration ofthe corrosion inhibiting agent when used in combination with a metalsalt or mixed metal salt may be less than about 5×10⁻¹ M, less thanabout 2×10⁻¹ M, less than about 10⁻¹ M, less than about 5×10⁻² M, lessthan about 2×10⁻² M, less than about 10⁻² M, less than about 5×10⁻³ M,less than about 2×10⁻³ M, or less than about 10⁻³ M. The concentrationrange of the corrosion inhibiting agent when used in combination with ametal salt or mixed metal salt may be from about 5×10⁻¹ M to about 10⁻⁸M, from about 2×10⁻¹ M to about 2×10⁻⁸ M, from about 10⁻¹ M to about5×10⁻⁸ M, from about 5×10⁻² M to about 10⁻⁷ M, from about 2×10⁻² M toabout 2×10⁻⁷ M, from about 10⁻² M to about 5×10⁻⁷ M, from about 5×10⁻³ Mto about 10⁻⁶ M, from about 2×10⁻³ M to about 2×10⁻⁶ M, from about 10⁻³M to about 5×10⁻⁶ M, or from about 5×10⁻⁴ M to about 10⁻⁵ M. Theconcentration of the metal salt or mixed metal salt when used incombination with a corrosion inhibiting agent may be less than about5×10⁻¹ M, less than about 2×10⁻¹ M, less than about 10⁻¹ M, less thanabout 5×10⁻² M, less than about 2×10⁻² M, less than about 10⁻² M, lessthan about 5×10⁻³ M, less than about 2×10⁻³ M, or less than about 10⁻³M. The concentration range of the metal salt or mixed metal salt whenused in combination with a corrosion inhibiting agent may be from about5×10⁻¹ M to about 10⁻⁸ M, from about 2×10⁻¹ M to about 2×10⁻⁸ M, fromabout 10⁻¹ M to about 5×10⁻⁸ M, from about 5×10⁻² M to about 10⁻⁷ M,from about 2×10⁻² M to about 2×10⁻⁷ M, from about 10⁻² M to about 5×10⁻⁷M, from about 5×10⁻³ M to about 10⁻⁶ M, from about 2×10⁻³ M to about2×10⁻⁶ M, from about 10⁻³ M to about 5×10⁻⁶ M, or from about 5×10⁻⁴ M toabout 10⁻⁵ M.

In one embodiment, the ratio of metal salt : corrosion inhibiting agentin the corrosion inhibitor composition is provided with an excess of themetal salt in comparison to the corrosion inhibiting agent. For example,the ratio of metal salt : corrosion inhibiting agent in the corrosioninhibitor composition may be greater than about 1:1, greater than about1.1:1, greater than about 1.2:1, greater than about 1.3:1, greater thanabout 1.4:1, greater than about 1.5:1, greater than about 1.6:1, greaterthan about 1.7:1, greater than about 1.8:1, greater than about 1.9:1,greater than about 2:1, greater than about 3:1, greater than about 4:1,greater than about 5:1, greater than about 6:1, greater than about 7:1,greater than about 8:1, greater than about 9:1, or greater than about10:1. The ratio of metal salt:corrosion inhibiting agent in thecorrosion inhibitor composition may be less than about 45:1, less thanabout 40:1, less than about 35:1, less than about 30:1, less than about25:1, less than about 20:1, less than about 15:1, or less than about10:1. The ratio of metal salt:corrosion inhibiting agent in thecorrosion inhibitor composition may be provided in a range of greaterthan about 1:1 to about 45:1, about 1.5:1 to about 40:1, about 2:1 toabout 35:1, about 2.5:1 to about 30:1, about 3:1 to about 25:1, about3.5:1 to about 20:1, about 4:1 to about 15:1, or about 5:1 to about10:1. For example, the ratio of metal salt:corrosion inhibiting agent inthe corrosion inhibitor composition may be provided in a range of about1.1:1 to about 45:1, about 1.2:1 to about 40:1, about 1.3:1 to about35:1, about 1.4:1 to about 30:1, about 1.5:1 to about 25:1, about 1.6:1to about 20:1, about 1.7:1 to about 15:1, about 1.8:1 to about 10:1,about 1.9:1 to about 9:1, or about 2:1 to about 8:1.

The corrosion inhibitor compositions are suitable for use andapplication to various substrates, such as metal substrates, and forexample can be provided as coating compositions. The compositions mayinclude one or more other additives or corrosion inhibiting agentssuitable for particular use with a type of substrate.

The corrosion inhibiting composition can be a coating compositioncomprising a film-forming organic polymer. The coating composition maybe a paint composition. The coating composition may comprise one or moreresins, for example epoxy based resins. The coating composition may be apaint composition, for example an epoxy resin based paint composition.

The coating composition may be a powder coating composition, for examplea powder coating composition suitable for use in powder coating ofvarious metal substrates including aluminium alloys as described hereinor steels.

The coating composition may be a spray composition.

The coating compositions can be applied to a substrate, in either a wetor “not fully cured” condition that dries or cures over time, that is,solvent evaporates. The coatings can dry or cure either naturally or byaccelerated means, for example an ultraviolet light cured system to forma film or “cured” paint. The coatings can also be applied in a semi orfully cured state, such as an adhesive.

The corrosion inhibiting composition can also be an encapsulatedcorrosion inhibiting composition. The encapsulated corrosion inhibitingcomposition may comprise at least one polymeric film encapsulating theat least one organic heterocyclic compound of Formula 1 as describedherein and at least one metal salt or mixed metal salt, wherein themetal is selected from rare earth, alkali earth and transition metals,as described herein, or any embodiments thereof. For example, theencapsulated corrosion inhibitor compositions may comprise at least onepolymeric film; at least one metal salt or mixed metal salt, wherein themetal is selected from the group consisting of Zn, La, Pr, Ce, Nd, Sm,Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr; andat least one organic heterocyclic compound of Formula 1 as describedherein or any embodiments thereof. The polymeric film may include apredetermined thickness and permeability to permit controlled diffusionof the particle ions upon interaction with water.

The corrosion inhibiting composition may be a corrosion inhibiting kit.The corrosion inhibiting kit may comprise two or more components and forexample include instructions that the compounds are mixed prior toapplication onto a metal substrate. For example a first component may beat least one organic heterocyclic compound of Formula 1 as describedherein and at least one metal salt or mixed metal salt, wherein themetal is selected from rare earth, alkali earth and transition metals,as described herein, or any embodiments thereof; and a second componentmay be a coating composition, for example a paint composition. The paintcomposition may be an epoxy based paint composition. A third componentmay be an additive, for example a hardener for the resin or any additivedescribed herein.

The compositions may include a list of ingredients, and/or components,and can also include a list of instructions for preparing and mixingtogether the ingredients, and/or components to make a coatingcomposition.

It will be appreciated that the compositions can include one or moreadditives, such as pigments, fillers and extenders. Examples of suitableadditives with which the corrosion inhibitors described herein can becombined include, for example, binders, solvents, pigments (includingsoluble or non-soluble extenders, fillers, corrosion-inhibitingpigments, and the like), solvents, additives (e.g., curing agents,surfactants, dyes, amino acids and the like), and so forth. Note thatsome additives can also properly be considered a pigment and vice versa(e.g., matting agents). More specifically, these “additives” include,but are not limited to, glycine, arginine, methionine, and derivativesof amino acids, such as methionine sulfoxide, methyl sulfoxide, andiodides/iodates, gelatin and gelatin derivatives, such as animal andfish gelatins, linear and cyclic dextrins, including alpha and betacyclodextrin, triflic acid, triflates, acetates, talc, kaolin,organic-based ionic exchange resins, such as organic-based cationic andanionic exchange resins, organic-based ionic exchange resins, such asorganic-based cationic and anionic exchange resins, organic-based ionicexchange resins that have been pre-exchanged or reacted with the salts,oxides, and/or mixed oxides of rare earth material, and metal sulfates,such as sulfates of rare earth materials, magnesium sulfate, calciumsulfate (anhydrous and hydrated forms), strontium sulfate, bariumsulfate, and the like, and combinations thereof.

It will be appreciated that the compositions may comprise, or consist ofany one or more of the components or additives described herein.

The compositions may also include other additives such as rheologymodifiers, fillers, tougheners, thermal or UV stabilizers, fireretardants, lubricants, surface active agents. The additive(s) areusually present in an amount of less than about 10% based on the totalweight of the activation treatment or the combination of solvent(s),agent(s) and additive(s). Examples include:

(a) rheology modifiers such as hydroxypropyl methyl cellulose (e.g.Methocell 311, Dow), modified urea (e.g. Byk 411, 410) andpolyhydroxycarboxylic acid amides (e.g. Byk 405);

(b) film formers such as esters of dicarboxylic acid (e.g. Lusolvan FBH,BASF) and glycol ethers (e.g. Dowanol, Dow);

(c) wetting agents such as fluorochemical surfactants (e.g. 3M Fluorad)and polyether modified poly-dimethyl-siloxane (e.g. Byk 307, 333);

(d) surfactants such as fatty acid derivatives (e.g. Bermadol SPS 2543,Akzo) and quaternary ammonium salts;

(e) dispersants such as non-ionic surfactants based on primary alcohols(e.g. Merpol 4481, Dupont) and alkylphenol-formaldehyde-bisulfidecondensates (e.g. Clariants 1494);

(f) anti foaming agents;

(g) anti corrosion reagents such as phosphate esters (e.g. ADD APT,Anticor C6), alkylammonium salt of (2-benzothiazolythio) succinic acid(e.g. Irgacor 153 CIBA) and triazine dithiols;

(h) stabilizers such as benzimidazole derivatives (e.g. Bayer, PreventolBCM, biocidal film protection);

(i) leveling agents such as fluorocarbon-modified polymers (e.g. EFKA3777);

(j) pigments or dyes such as fluorescents (Royale Pigment andchemicals);

(k) organic and inorganic dyes such as fluoroscein; and

(l) Lewis acids such as lithium chloride, zinc chloride, strontiumchloride, calcium chloride and aluminium chloride.

(m) Suitable flame retardants which retard flame propagation, heatrelease and/or smoke generation which may be added singularly oroptionally include:

-   -   Phosphorus derivatives such as molecules containing phosphate,        polyphosphate, phosphites, phosphazine and phosphine functional        groups, for example, melamine phosphate, dimelamine phosphate,        melamine polyphosphate, ammonia phosphate, ammonia        polyphosphate, pentaerythritol phosphate, melamine phosphite and        triphenyl phosphine.    -   Nitrogen containing derivatives such as melamine, melamine        cyanurate, melamine phthalate, melamine phthalimide, melam,        melem, melon, melam cyanurate, melem cyanurate, melon cyanurate,        hexamethylene tetraamine, imidazole, adenine, guanine, cytosine        and thymine.    -   Molecules containing borate functional groups such as ammonia        borate and zinc borate.    -   Molecules containing two or more alcohol groups such as        pentaerythritol, polyethylene alcohol, polyglycols and        carbohydrates, for example, glucose, sucrose and starch.    -   Molecules which endothermically release non-combustible        decomposition gases, such as, metal hydroxides, for example,        magnesium hydroxide and aluminum hydroxide.    -   Expandable graphite.

Method of Selecting Corrosion Inhibitor Compositions

The present disclosure also relates to a method for selecting corrosioninhibitor compositions for inhibiting corrosion.

The main goal in the method is to establish a selection of (a) at leastone organic heterocyclic compound of Formula 1 as described herein; and(b) at least one metal salt or mixed metal salt, wherein the metal isselected from rare earth, alkali earth and transition metals, asdescribed herein, or any embodiments thereof, using a high throughputscreening technique.

The rapid screening method provides the following advantages: (1) it israpid, for example it reduces the time per experiment and increases thenumber of experiments per unit time, (2) it reduces the preparation timeper experiment and also reduces the time taken for the analysis ofresults and (3) it correlates with existing corrosion standards ortesting methods. From an environmental viewpoint, the amount of materialand solutions used and requiring disposal is significantly reduced usingthe described rapid screening method.

The rapid screening of corrosion inhibitor compositions may take placein a sodium chloride (NaCl) solution and at room temperature for 24hours in an eighty-eight well polydimethylsiloxane block (PDMS) broughtinto contact with the surface of a metal substrate. The metal substratemay be a copper-containing alloy, such as copper-containing aluminiumalloy. The NaCl solutions may be prepared at concentrations from about10⁻¹ to about 10⁻⁶ M.

The rapid screening test allows for corrosion analysis of the corrosioninhibitor compositions through imaging. Image processing is importantfor this technique because of the need to capture all of the corrosiondamage in one image for processing. The semi-quantitative image analysistechnique simultaneously analyses the corrosion to match the corrosionseen visually. Two photographs of the sample under different lightingconditions are combined using layers and inverse images in AdobePhotoShop® to convert the resulting corrosion to a brightness value andthen sample mask and background mask images are created for analysis.The observed corrosion is converted to corrosion values over a 0-10scale with repetitions over 4 plates and multiple repetitions per plateconsistently within 10% of each other.

EXAMPLES

In order that the present disclosure may be more clearly understood,embodiments of the disclosure are described in further detail below byreference to the following non-limiting experimental materials,methodologies, and examples.

General Procedure for the Rapid Screening of Corrosion InhibitorCompositions

The corrosion inhibitor compositions include a mixture of at least onemetal salt or mixed metal salt with at least one corrosion inhibitingagent, as described herein. Each metal salt or mixed metal salt wasadded into solution of 0.1 M NaCl in deionised water at a concentrationof 10⁻³ M, 5×10⁻⁴ M, 2×10⁻⁴ M, 10⁻⁴ M, 5×10⁻⁵ M, 2×10⁻⁵ M, and 10⁻⁵ M.Each corrosion inhibiting agent was added into solution of 0.1 M NaCl indeionised water at a concentration of 10⁻³ M, 5×10⁻⁴ M, 2×10⁻⁴ M, 10⁻⁴M, 5×10⁻⁵ M, 2×10⁻⁵ M, and 10⁻⁵ M.

A final volume of 200 μL of the corrosion inhibitor composition wereadded to an eighty-eight well polydimethylsiloxane block (PDMS) broughtinto contact with a surface of a metal substrate. The corrosioninhibitor compositions comprise various combinations of metal salt ormixed metal salt with corrosion inhibiting agent, wherein the rangesinclude between 1:1 to 45:1 of metal salt:corrosion inhibiting agent.

The corrosion experiments were then allowed to proceed for 24 hours atroom temperature (20° C.). During the experiment the holes were looselycovered with a plastic film to prevent the corrosion inhibitorcompositions from evaporation while allowing diffusion of air.

At the end of the 24 hour period, the assembly was inverted, thecorrosion inhibitor compositions discarded and each well washed withdeionized water. The assembly was disassembled and the PDMS rubberremoved. The corrosion circles on the plate were washed again and excessliquid removed with compressed air. The metal substrate was left to dryfor 12 hour in a desiccator containing self-indicating silica gel atroom temperature before imaging.

Two photographs of the sample under different lighting conditions arecombined using layers and inverse images in Adobe PhotoShop® to convertthe resulting corrosion to a brightness value and then sample mask andbackground mask images are created for analysis. The brightness valueswere ranked from 0 (darkest, least amount of corrosion) to 100(brightest, most amount of corrosion). The observed corrosion isconverted to corrosion values over a 0-10 scale with repetitions over 4plates and multiple repetitions per plate consistently within 10% ofeach other. Typically, a value of 0 represents the least amount ofcorrosion and a value of 10 represents the most amount of corrosion.

In FIG. 1 a and FIG. 1 b a table of corrosion values over a 0-10 scalefrom the 24 hour wells rapid screening method for various corrosioninhibitor compositions is shown. The selection of corrosion inhibitorcomposition is selected from (a) corrosion inhibiting agents of Formula1, compounds 12, 13, 16, and 17, and (b) metal salt or mixed metal salt,Ce and Zn, as described herein, and provided at various concentrations.Comparison corrosion values are also shown for the same selection ofcorrosion inhibiting agents and metal salts or mixed metal salts. FIG. 1a and FIG. 1 b shows the rapid screening method performed on thecopper-containing aluminium alloy, AA7075. The concentration of themetal salts shown in FIG. 1 b are the same as the concentration of themetal salts shown in FIG. 1 a.

In FIG. 2 a and FIG. 2 b a table of corrosion values over a 0-10 scalefrom the 24 hour wells rapid screening method for various corrosioninhibitor compositions is shown. The selection of corrosion inhibitorcomposition is selected from (a) corrosion inhibiting agents of Formula1, compounds 12, 13, 16, and 17, and (b) metal salts, Ce and Zn asdescribed herein, and provided at various concentrations. Comparisoncorrosion values are also shown for the same selection of corrosioninhibiting agents and metal salt or mixed metal salt. FIG. 2 a and FIG.2 b shows the rapid screening method performed on a copper-containingaluminium alloy, AA2024. The concentration of the metal salts shown inFIG. 2 b are the same as the concentration of the metal salts shown inFIG. 2 a.

Example 1a

CeCl₃.7H₂O and Compound 16 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA7075 type metalsubstrate, and analysed according to the general process describedabove. FIG. 1 a shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 1b

ZnCl₂ and Compound 16 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA7075 type metal substrate, andanalysed according to the general process described above. FIG. 1 ashows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 2a

CeCl₃.7H₂O and Compound 17 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA7075 type metalsubstrate, and analysed according to the general process describedabove. FIG. 1 a shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 2b

ZnCl₂ and Compound 17 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA7075 type metal substrate, andanalysed according to the general process described above. FIG. 1 ashows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 3a

CeCl₃.7H₂O and Compound 12 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA7075 type metalsubstrate, and analysed according to the general process describedabove. FIG. 1 b shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 3b

ZnCl₂ and Compound 12 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA7075 type metal substrate, andanalysed according to the general process described above. FIG. 1 bshows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 4a

CeCl₃.7H₂O and Compound 13 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA7075 type metalsubstrate, and analysed according to the general process describedabove. FIG. 1 b shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 4b

ZnCl₂ and Compound 13 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA7075 type metal substrate, andanalysed according to the general process described above. FIG. 1 bshows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 5a

CeCl₃.7H₂O and Compound 16 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA2024 type metalsubstrate, and analysed according to the general process describedabove. FIG. 2 a shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 5b

ZnCl₂ and Compound 16 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA2024 type metal substrate, andanalysed according to the general process described above. FIG. 2 ashows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 6a

CeCl₃.7H₂O and Compound 17 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA2024 type metalsubstrate, and analysed according to the general process describedabove. FIG. 2 a shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 6b

ZnCl₂ and Compound 17 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA2024 type metal substrate, andanalysed according to the general process described above. FIG. 2 ashows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 7a

CeCl₃.7H₂O and Compound 12 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA2024 type metalsubstrate, and analysed according to the general process describedabove. FIG. 2 b shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 7b

ZnCl₂ and Compound 12 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA2024 type metal substrate, andanalysed according to the general process described above. FIG. 2 bshows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

Example 8a

CeCl₃.7H₂O and Compound 13 was prepared and transferred to theeighty-eighty well PDMS brought into contact with AA2024 type metalsubstrate, and analysed according to the general process describedabove. FIG. 2 b shows that the combination provides results supportingadvantages provided by the combination, which are particularlysynergistic across various concentration ranges.

Example 8b

ZnCl₂ and Compound 13 was prepared and transferred to the eighty-eightywell PDMS brought into contact with AA2024 type metal substrate, andanalysed according to the general process described above. FIG. 2 bshows that the combination provides results supporting advantagesprovided by the combination, which are particularly synergistic acrossvarious concentration ranges.

General Procedure for the Polarisation Resistance Electrochemical Tests

The corrosion inhibitor composition includes a mixture of at least onemetal with at least one corrosion inhibiting agent of Formula 1, asdescribed herein. Each metal was added into solution of 0.1 M NaCl indeionised water at a concentration of 10⁻³ M, 5×10⁻⁴ M, 2×10⁻⁴ M, 10⁻⁴M, 5×10⁻⁵ M, 2×10⁻⁵ M, and 10⁻⁵ M. Each corrosion inhibiting agent wasadded into solution of 0.1 M NaCl in deionised water at a concentrationof 10⁻³ M, 5×10⁻⁴ M, 2×10⁻⁴ M, 10⁻⁴ M, 5×10⁻⁵ M, 2×10⁻⁵ M, and 10⁻⁵ M.

The metal substrate (3 cm×3 cm surface area) was abraded using finegrade 3M Scotchbrite. Metal substrates, for example AA2024 and AA7075,were rinsed with deionised water and air dried. A titanium mesh andsaturated calomel electrode (SCE) constituted the counter and referenceelectrodes respectively to be coupled with the working electrode to forma standard 3-electrode cell. Each corrosion inhibitor composition wasleft at an open circuit potential (OCP) period of 5 minutes prior tostarting the polarisation scan. Linear polarization was measured over apotential range of ±10 mV vs. OCP at a scan rate of 0.167 mV/s everyhour for 168 hours. Values of polarization resistance, R_(p), werededuced from the slope of fitted current density vs. potential lines.The tests were performed in 180 ml solutions open to air for 168 hours.The polarisation experiments were performed using a 16 channel-VMP3(variable multichannel potentiostat) with the EC-lab software v10.4.

Example 9

ZnCl₂ and Compound 17 was prepared and analysed according to the generalprocess described above. The metal substrate was AA2024 and prepared asdescribed above. FIG. 3 shows that the combination provides anunexpected synergistic result over the individual components.

Example 10

ZnCl₂ and Compound 17 was prepared and analysed according to the generalprocess described above. The metal substrate was AA7075 and prepared asdescribed above.

Example 11

CeCl₃.7H₂O and Compound 23 was prepared at a concentration of 10⁻⁴ M andanalysed according to the general procedure described above. PrCl₃.6H₂Oand Compound 23 was prepared at a concentration of 10⁻⁴ M and analysedaccording to the general procedure described above. The metal substratewas AA2024 and prepared as described above. The combinations werecompared to the industry standard corrosion inhibitor, K₂Cr₂O₇, solutionof 0.1 M NaCl at 10⁻⁴ M. The results observed from the combinations wereshown to have significantly enhanced corrosion inhibition propertiesover the industry standard corrosion inhibitor.

Example 12

CeCl₃.7H₂O and Compound 23 was prepared at a concentration of 10⁻⁴ M andanalysed according to the general procedure described above. PrCl₃.6H₂Oand Compound 23 was prepared at a concentration of 10⁻⁴ M and analysedaccording to the general procedure described above. The metal substratewas AA7075 and prepared as described above. The combinations werecompared to the industry standard corrosion inhibitor, K₂Cr₂O₇, solutionof 0.1 M NaCl at 10⁻⁴ M. The results observed from the combinations wereshown to have significantly enhanced corrosion inhibition propertiesover the industry standard corrosion inhibitor.

Example 13

CeCl₃.7H₂O was prepared at a concentration of 10⁻⁴ M and Compound 23 wasprepared at a concentration of 2×10⁻⁵ M, and analysed according to thegeneral procedure described above. PrCl₃.6H₂O was prepared at aconcentration of 10⁻⁴ M and Compound 23 was prepared at a concentrationof 2×10⁻⁵ M, and analysed according to the general procedure describedabove. The metal substrate was AA2024 and prepared as described above.The combinations were compared to the industry standard corrosioninhibitor, K₂Cr₂O₇, solution of 0.1 M NaCl at 10⁻⁴ M. The resultsobserved from the combinations were shown to have significantly enhancedcorrosion inhibition properties over the industry standard corrosioninhibitor.

Example 14

CeCl₃.7H₂O was prepared at a concentration of 10⁻⁴ M and Compound 23 wasprepared at a concentration of 2×10⁻⁵ M, and analysed according to thegeneral procedure described above. PrCl₃.6H₂O was prepared at aconcentration of 10⁻⁴ M and Compound 23 was prepared at a concentrationof 2×10⁻⁵ M, and analysed according to the general procedure describedabove. The metal substrate was AA7075 and prepared as described above.The combinations were compared to the industry standard corrosioninhibitor, K₂Cr₂O₇, solution of 0.1 M NaCl at 10⁻⁴ M. The resultsobserved from the combinations were shown to have significantly enhancedcorrosion inhibition properties over the industry standard corrosioninhibitor.

1. A method of protecting a substrate from corrosion, comprising:applying a corrosion inhibitor composition to a surface of a substrate,wherein the corrosion inhibitor composition comprises: at least onemetal salt or mixed metal salt, wherein the metal is selected from thegroup consisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,Yb, Lu, Co, Y, Sc, Zr, and combination(s) thereof; and at least onecorrosion inhibiting agent selected from an organic heterocycliccompound of Formula 1:

wherein: A is fused with one or more aryl or heteroaryl rings to form aring selected from the group consisting of a purine and a benzimidazole,wherein the ring is optionally substituted with one or moresubstituents, wherein a dotted line represents one or more optionaldouble bonds; Y¹ is selected from the group consisting of S or SH,wherein the dotted line represents a double bond when Y¹ is S or isabsent when Y¹ is SH; X¹ is selected from the group consisting of N andNH; X² is selected from the group consisting of N and NR⁵; and R⁵ isselected from the group consisting of hydrogen, amino, C₁-C₁₀alkyl,C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl, and heteroaryl, wherein amino,alkyl, alkenyl, alkynyl, aryl, or heteroaryl is optionally substituted.2. The method of claim 1, wherein each of the metal salt or mixed metalsalt and the corrosion inhibiting agent are provided as individualcomponents in the composition and not a preformed metal-organic complex.3. The method of claim 2, wherein a ratio of metal salt:corrosioninhibiting agent in the corrosion inhibitor composition is provided withan excess of the metal salt in comparison to the corrosion inhibitingagent.
 4. The method of claim 1, wherein Y¹ is SH.
 5. The method ofclaim 1, wherein X¹ is N.
 6. The method of claim 1, wherein X² is NH. 7.The method of claim 1, wherein the metal is selected from at least oneof La, Pr, Ce, Co, and Y.
 8. The method of claim 1, wherein the metal isselected from at least one of Zn, Pr and Ce.
 9. The method of claim 1,wherein the substrate is a copper-containing metal substrate.
 10. Themethod of claim 1, wherein A is fused with one or more aryl orheteroaryl rings to form a ring that is a purine.
 11. The method ofclaim 1, wherein A is fused with one or more aryl or heteroaryl rings toform a ring that is a benzimidazole.
 12. A composition for protectingsubstrates from corrosion, wherein the composition comprises: at leastone metal salt or mixed metal salt, wherein the metal is selected fromthe group consisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er,Tm, Yb, Lu, Co, Y, Sc, Zr, and combination(s) thereof; and at least onecorrosion inhibiting agent selected from an organic heterocycliccompound of Formula 1:

wherein: A is fused with one or more aryl or heteroaryl rings to form aring selected from the group consisting of a purine and a benzimidazole,wherein the ring is optionally substituted with one or moresubstituents, wherein a dotted line represents one or more optionaldouble bonds; Y¹ is selected from the group consisting of S or SH,wherein the dotted line represents a double bond when Y¹ is S or isabsent when Y¹ is SH; X¹ is selected from the group consisting of N andNH; X² is selected from the group consisting of N and NR⁵; and R⁵ isselected from the group consisting of hydrogen, amino, C₁-C₁₀alkyl,C₂-C₁₀alkenyl, C₂-C₁₀alkynyl, aryl, and heteroaryl, wherein amino,alkyl, alkenyl, alkynyl, aryl, or heteroaryl is optionally substituted.13. The composition of claim 12, wherein each of the metal salt or mixedmetal salt and the corrosion inhibiting agent are provided as individualcomponents in the composition and not a preformed metal-organic complex.14. The composition of claim 12, wherein a ratio of metal salt:corrosioninhibiting agent in the corrosion inhibitor composition is provided withan excess of the metal salt in comparison to the corrosion inhibitingagent.
 15. The composition of claim 12, wherein the composition has aconcentration of the corrosion inhibiting agent of about 10⁻³ M to about5×10⁻⁶ M.
 16. The composition of claim 12, wherein the composition has aconcentration of the metal of about 10⁻³ M to about 5×10⁻⁶ M.
 17. Thecomposition of claim 12, wherein the composition further comprises anorganic polymer.
 18. The composition of claim 18, wherein the organicpolymer comprises one or more epoxy based resins.
 19. The method ofclaim 12, wherein A is fused with one or more aryl or heteroaryl ringsto form a ring that is a purine.
 20. The method of claim 12, wherein Ais fused with one or more aryl or heteroaryl rings to form a ring thatis a benzimidazole.